If a battle that's being attacked somehow stops being a battle, it is removed from combat
the ability still resolves
I started collecting Pikachu cards exactly a year ago (October 2015), and when I saw the Bulbapedia list I was already suprised to see so many cool cards I had never seen before
Most cards that are able to ready a character are restricted from questing multiple times, but Beast is free to quest multiple times, making it a truly dangerous card that can end the game by scoring four or six Lore in a flash
You could also go with a long term plan model: Test of Patience R Sorcery (R) Search your library for a card, shuffle your library, then shuffle that card into the top three cards of your library
It doesn't have any inherent rules meaning, but some Gates, including some found in this set, have abilities that care either about which other Gates you control or the number of other Gates you control